This invention relates to thin-filmed deposition apparatus, and more particularly, to such an apparatus including easily removable racks to which substrates may be fitted.
U.S. Pat. No. 3,643,625 to Mahl (assigned to the assignee of this invention) discloses a thin-film deposition apparatus including a plurality of racks, each having a circular outer periphery which is in contact with a support ring and mounted within a vacuum chamber. The racks are rotatably mounted to respective arms of a spider or holder which is provided with a central hub, to which the downwardly and outwardly curved arms are fixed.
As seen in the disclosure of that patent, the substrates are fitted to a rack inwardly of the concave surface thereof, and it will be seen that such concave surface of each rack is relatively difficult to reach, resulting in a relatively great consumption of time in the application and removal of such substrates in situ. As a practical alternative, a rack is normally slipped downwardly of a collar at the end of an arm, and removed entirely from the apparatus, for loading of that rack. Yet it will be seen that this is also a relatively inconvenient operation, requiring moving of, for example, the spider relative to the ring, and awkward movement of the other racks which may be undesired, or difficult to accomplish.
Removal and replacement of individual racks is a twohanded operation and requires average or better than average manual dexterity. Also, because of the relatively large size of the apparatus short or short-armed individuals can not generally successfully carry out the removal and replacement operation. Further, a special tool is generally needed to remove and replace the individual racks since they are relatively heavy (making it difficult to support their weights from the rims thereof), and must usually have a central support pin thereof blindly slid into a hole. This blind insertion of the pin into the hole can, of course, lead to galling which can require replacement or repair of parts. Thus, what results is a relatively slow and difficult operation which can damage the apparatus.
It will also be seen that in accordance with that disclosure, the entire spider with the racks mounted thereon can, and in practice often is, lifted as a sub-assembly from the support ring. This, however, required overhead removal of this sub-assembly can only be accomplished if a rather large overhead clearance is provided as by making the vacuum jar move well overhead. Yet, because of the particular construction involved, it will be seen that an individual arm and rack assembly can not be removed independently of the others as a unit.
Of more general interest is U.S. Pat. No. 3,128,205, wherein racks themselves are not in contact with a support ring. Rather, each rack has fixed thereto a disc, the outer periphery of which is in rolling engagement with a wheel. In each of the aforementioned patents, it is clear that the support rings, and wheel, respectively serve as means for imparting rotary motion to the racks on rotation of the spider.
It is accordingly an object of this invention to provide a thin-film deposition apparatus including a plurality of racks, wherein each rack may be readily removed in a highly convenient manner for loading and unloading thereof.
It is another object of the present invention to provide apparatus which, while fulfilling the above object, can have the angles of the axes of the racks, relative to a vertical centerline of the apparatus, changed by simple moving or replacement of the support ring.
It is a further object of this invention to provide apparatus which, while fulfilling the above objects, is simple in design, effective in use, and much faster to use than prior art apparatus.
Broadly stated, the invention is in a thin-film deposition apparatus comprising rotatable means, a plurality of racks each having a circular outer periphery, a plurality of arm means, each rack being rotatably mounted relative to an arm means, each arm means being operatively associated with the rotatable means, and means for imparting rotary motion to the racks about their centers responsive to rotation of the rotatable means. The improvement comprises means operatively coupling each arm means and the rotatable means for allowing removal of an individual arm means from the rotatable means.